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Radio dishes are pointed skyward at the Australian Telescope Compact Array at the Paul Wild Observatory. Today, radio astronomy is the focus of the search for extraterrestrial intelligence, or SETI. But that may not always be the case.

LONDON — This month the Royal Society held a two-day meeting to work out a "scientific and societal agenda" on extraterrestrial life, following up on a similar meeting in January. The discussions generated controversy, conspiracy theories and a little bit of acrimony. So what happened? I was there on both days, and here's the inside story.

Scientists are searching for extraterrestrial life in a number of different ways and places. One aspect of this is the search for extrasolar planets, on the basis that an Earthlike planet around a sunlike star might be a good place to look. The first super-Earths have been discovered, and the longer-term goal will be to undertake spectral analysis of the atmospheres of such exoplanets, looking for oxygen, ozone, water and other potential indicators of life. The recent excitement over Gliese 581g brings such work into focus — though even the very existence of this world is now the matter of some debate.

Other scientists believe our best chance of discovering alien life will be a human or robotic mission in our own solar system — probably to Mars — targeted at detecting extraterrestrial microbial life. But the controversy begins with the small but vociferous group of scientists who use radio telescopes to search the sky for a signal from other civilizations.

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Nick Pope worked for the British Ministry of Defense for 21 years, and one of his jobs involved investigating UFO sightings. He now works as a freelance journalist and media commentator.

The radio search for extraterrestrial intelligence, or SETI, is celebrating its 50th anniversary this year. The lack of results has led to a reassessment of search strategies. Some exotic ideas about where to look and what to look for were discussed at the Royal Society meeting. Clement Vidal, a researcher at the Free University of Brussels, speculated that advanced civilizations might migrate toward black holes, not least because they represent the ultimate energy source. Steven Dick, formerly NASA’s chief historian, speculated that we might be living in a post-biological universe, dominated by artificial intelligence, on the basis that intelligences would be driven to improve and perpetuate.

When I heard the phrase "immortal thinking machines," I had to remind myself that I was at the Royal Society, not a sci-fi convention.

So what happens if SETI find a signal? Do we reply? Though not present, the shadow of Professor Stephen Hawking loomed large over the meeting. Earlier this year Hawking warned bluntly that contacting aliens could have catastrophic consequences for the human race. He likened this to the arrival of Christopher Columbus in the New World, and pointed out that matters didn’t turn out too well for the Native Americans. This echoed a remark made at the Royal Society’s January conference, when Professor Simon Conway Morris, a Cambridge University palaeontologist, said "if the cosmic phone rings, don’t answer."

Related to this question is the issue of active SETI, sometimes known as METI (messaging to extraterrestrial intelligence). This was discussed extensively at this month’s meeting, and that’s when things got heated.

Some SETI scientists want to move into METI. One reason is the theory that extraterrestrials might not initiate contact, but might respond to a message we send. Some METI has already been done – for example, the "Cosmic Calls" transmitted in 1999 and 2003 from the Evpatoria radar installation in Ukraine under the supervision of Alexander Zaitsev.

The SETI Institute's "Earth Speaks" project has attempted to engage the public on this and asks for suggestions on what we might transmit. The messages range from the poignant to the amusing, with my favorite being "Hi, be careful, we are deadly and it’s pretty boring here anyway so don’t bother coming."

Author and futurist David Brin felt strongly that there ought to be a moratorium on METI, until such time as an informed debate could take place. There was talk of "sages" being consulted, but no consensus on who those sages might be, or whether the other 6 billion of us might get a say. Brin felt objectors to METI were being ridiculed with Hollywood stereotypes about evil aliens and said this showed a disappointing lack of imagination. He asked what was wrong with having a debate on the subject, as such a debate would be responsible, interesting and fun.

Science editor Alan Boyle's blog: "Astronaut Abby" is at the controls of a social-media machine that is launching the 15-year-old from Minnesota to Kazakhstan this month for the liftoff of the International Space Station's next crew.

Seth Shostak, senior astronomer at the SETI Institute, took the opposite view. He said that any attempts to proscribe METI were rooted in paranoia and would be anti-science. He saw no point in any consultation process, because it wasn’t clear who would have the right to decide, or how it would help us pick the right answer. He also wondered how, short of going to war, any moratorium could be enforced. Shostak and others have pointed out that the horse has left the barn long ago and that we’ve been a detectable civilization for decades anyway, due to our FM, television and radar signals. This point is disputed, but the question is unanswerable at present. We don’t know how big or powerful alien radio telescopes might be – if indeed such things exist.

Such are the debates that bedevil the SETI community, where scientists speculate about something which they can’t study and which we don’t even know is there at all.

The closest thing there is to any regulation of all this is the SETI community’s “Declaration of Principles Concerning the Conduct of the Search for Extraterrestrial Intelligence.” This revised document was unanimously adopted by the SETI Permanent Study Group of the International Academy of Astronautics on Sept. 30. It states that “In the case of the confirmed detection of a signal, signatories to this declaration will not respond without first seeking guidance and consent of a broadly representative international body, such as the United Nations”. However, none of this covers METI – and in any case, the agreement is between individuals and non-governmental organisations, not between nations.

One of the speakers at the Royal Society meeting was Professor Mazlan Othman, a Malaysian astrophysicist who is director of the U.N. Office for Outer Space Affairs. The week before the meeting, numerous media outlets carried a story that she was being appointed an “alien ambassador” – a spokeswoman for Planet Earth if E.T. comes calling. Rumors flew around the UFO and conspiracy theory communities that an alien signal had been detected and that an announcement was imminent. The Royal Society meeting itself was seen as being part of this process, and when the alien ambassador story was denied, this started rumors of a cover-up.

At the meeting, Othman made it clear that the story was false and derived from a mistaken interpretation of the point she did make – that is, that her U.N. office and the U.N. Committee on the Peaceful Uses of Outer Space, or COPUOS, might be appropriate forums for managing the global response to the discovery of extraterrestrial life.

Othman set out some ideas on the process whereby the various issues that would arise from the discovery or detection of extraterrestrial life – scientific, societal, legal and ethical – might be brought to the U.N. As a potential precedent for this process, she referred to the issue of potentially threatening near-Earth objects, which is being addressed by experts working with COPUOS and other organizations.

Her message was clear: "Come to COPUOS with a degree of consensus." But as the row over METI illustrates, we are a long way from consensus. Expect some interesting debates over the next few months and ... watch this space!

Nick Pope worked for the British Ministry of Defense for 21 years, and one of his jobs involved investigating UFO sightings. He now works as a freelance journalist and media commentator, covering wide range of subjects including the unexplained, conspiracy theories, space and science fiction.

Somewhere out there, alien civilizations might be communicating with each other. They might even be trying to contact us. In 1960, this reasoning compelled astronomer Frank Drake to point a radio telescope at the stars and listen for chatter. He didn't hear E.T. calling us, calling home, or calling anywhere else during his four-month-long experiment at the National Radio Astronomy Observatory in Green Bank, W.Va., but the effort officially kicked off what is known as SETI, the search for extraterrestrial intelligence. Click the "Next" label to check out highlights from the first 50 years of the search.

— By John Roach, msnbc.com contributor

1974: Earthlings send message to aliens

By 1974, Drake and his colleagues still hadn't heard anything from ET, but they hadn't given up hope. Instead, they sent a message out to the aliens with the Arecibo radio telescope in Puerto Rico, the first deliberate message sent from Earth out to the stars. The message contained information about life-giving chemicals, DNA, a simple drawing of our solar system, and pictures of human beings and the Arecibo telescope. The string of 1's and 0's was sent to a group of about 300,000 stars in called the Great Cluster in Hercules, Messier 13, about 25,000 light years away.

Did E.T. make a prank call to Earth on Aug. 15, 1977? We may never know for sure, but astronomer Jerry Ehman was struck enough by a string of letters and numbers on a printout of radio data from the Big Ear Radio Observatory at Ohio State University to scribble "Wow!" in the margin. The extraordinary signal might have been E.T., or something else. Whatever it was, astronomers have been unable to find it again despite dozens of searches, leaving open the possibility that E.T. called but hung up after the first ring.

1992-1993: NASA's brief search

U.S. Senate Historical Office

Exactly 500 years after Christopher Columbus arrived in the New World, NASA officially launched its SETI program, the High Resolution Microwave Survey. Experts called it the most ambitious and technologically advanced alien-search effort ever conducted, but after just a year of operation the program was squashed. Sen. Richard Bryan, D-Nev., shown here, led the effort to kill the program, telling the Senate that "millions have been spent and we have yet to bag a single little green fellow. Not a single Martian has said take me to your leader, and not a single flying saucer has applied for FAA approval."

1995: Project Phoenix rises from ashes

Seth Shostak / SETI Institute

When NASA funding for alien searches ran dry, private enterprise picked up the pieces - including some of NASA's equipment - and launched Project Phoenix. The targeted search focused on about 1,000 stars thought most likely to harbor alien civilizations and was conducted at various radio astronomy observatories around the world. In this image, SETI Institute astronomer Seth Shostak looks for E.T.'s call on a computer bank at the Arecibo observatory in Puerto Rico.

Five million Internet users have contributed more than 3 million years of processing time to the search for signals from extraterrestrial civilizations through the SETI @ Home screensaver program, shown here.

Hundreds, then thousands, and ultimately millions of computer users around the world got in on the search for E.T. with the 1999 launch of SETI@home, a distributed computing project run at the University of California at Berkeley. The program enlists personal computers to sort through the mountains of SETI data, one chunk at a time, collected by the Arecibo radio telescope. The combined power of all the computers running the program essentially acts like a super duper supercomputer, but at a fraction of the cost.

2007: Telescope array turned on

For most of the past 50 years, SETI projects have required astronomers to wait in line for time on giant radio telescopes around the world. That changed in 2007 with the opening of the Allen Telescope Array, a constellation of 42 radio telescopes with 20-foot-wide dishes in the scrublands about 300 miles northeast of San Francisco. The array, privately financed by software billionaire Paul Allen and others, puts the search for E.T. front and center. The project is jointly run by the SETI Institute and the University of California at Berkley. In the coming decades the array may grow to 350 antennas, making it one of the most powerful radio telescopes in the world.

The future of SETI

NASA

An artist's interpretation of the Kepler observatory in space. Credit: NASA

As of this writing, extraterrestrials remain elusive, assuming that they exist at all. Given that the search is only 50 years old, many astronomers see little reason to despair - things are just getting going. NASA recently lent a new hand to the search with its Kepler mission, a space telescope that is looking for Earthlike, habitable planets around thousands of stars in our Milky Way galaxy. Detection of these planets will help SETI scientists focus their efforts.

Other ideas include a push to expand the search beyond just radio signals. Paul Davies, a physicist at Arizona State University and author of several popular science books, argues that messages from E.T. might even be floating around in the junk DNA of terrestrial organisms and that we should start searching decoded genomes for the biotech equivalent of a message in a bottle.